Soluble tumor necrosis factor-alpha receptor type 1 during selenium supplementation in psoriasis patients

Abstract

Objective: Tumor necrosis factor-alpha (TNF-alpha) and its receptors play important roles in the induction and maintenance of psoriatic lesions. Selenium (Se), a trace element with immunomodulatory properties, is usually decreased in psoriasis patients. We examined the influence of Se supplementation on soluble TNF-alpha receptor type 1 (sTNF-R1) and topical treatment in psoriasis patients.

Methods: The study was conducted in between January and June 2002. Twenty-two inpatients with active plaque psoriasis received topical treatment with 5% salicylic acid ointment, 0.1% to 0.3% dithranol ointment, and 200 microg daily of Se as selenomethionine (SeMet; n = 11, group 1) or placebo (n = 11, group 2) for 4 wk. Psoriasis Area and Severity Index (PASI) score and Se and sTNF-R1 concentrations were assessed at baseline and every 2 wk. Control sera were obtained from 10 healthy subjects. For statistical analysis, parametric tests were used, and the level of significance was set at P = 0.05.

Results: The baseline sTNF-R1 levels were 1.87 +/- 0.58 ng/mL (1.98 +/- 0.44 ng/mL in group 1 and 1.75 +/- 0.69 ng/mL in group 2, P = 0.34) in psoriasis patients and 1.65 +/- 0.25 ng/mL in control subjects (P = 0.17); baseline Se concentrations were 48.31 +/- 13.20 microg/L (48.31 +/- 13.20 microg/L in group 1 and 50.35 +/- 13.49 microg/L in group 2, P = 0.41) in psoriasis patients and 58.30 +/- 17.21 microg/L in control subjects (P = 0.05). A positive correlation between PASI and sTNF-R1 was noticed (r = 0.36, P = 0.04; r = 0.51 in group 1 and r = 0.18 in group 2). After 4 wk, almost complete remission of skin lesions was achieved in both groups, but the PASI score was higher in group 1 than in group 2 (4.30 +/- 3.92 and 1.67 +/- 1.17, respectively; P < 0.05). TNF-R1 levels were 1.81 +/- 0.42 ng/mL in group 1 and 1.33 +/- 0.40 ng/mL in group 2 (P = 0.01), and the correlation between PASI score and TNF-R1 level became inverse (r = -0.24 in group 1 and r = -0.59 in group 2). Se concentrations were 107.51 +/- 18.08 microg/L in group 1 and 56.83 +/- 15.32 microg/L in group 2 (P < 0.01).

Conclusions: Increased level of sTNF-R1 may be an indicator of active psoriasis. Supplementation with selenomethionine was ineffective as adjuvant treatment in plaque psoriasis and may contribute to the maintenance of elevated TNF-R1 concentration in psoriasis patients despite the remission of skin lesions.